CM4 unable to detect its USB2.0 hub
With current rpi4-mainline kernel, the USB2.0 hub is unable to be detected.
This means the connect keyboard is completely unusable.
It's not a big deal as the CM4 is currently acting as a headless VM server. But it can be annoying when something went wrong and needs to fallback into the recovery shell.
It looks like a upstream bug though, as the EDK2 UEFI firmware seems to have the same problem.